A furry little squirrel poked its beady eyes from behind a tree trunk before darting away. A plastic model of an Asian Longhorn Beetle perched on a branch, beside a sign warning visitors not to ship firewood across state lines into Massachusetts. A large crow perched on a branch, grooming itself.

Educator Alex Dunn explained that the Walkway – the first in the U.S. and only one in New England – was designed to provide an educational experience that, along with being fun, would help visitors understand "what it’s like to be a real canopy researcher.’’

"It’s more than just an adventure. There’s plenty of zip lines around,’’ he said. "We hope people will come away with an new appreciation of the beauty and complexity of a sub-habitat in a small forest.’’

Built in 1999, the Tree Canopy Walkway consists of four stationary wooden platforms built onto the oaks and hickories in the small forest and is connected by rope suspension bridges, perhaps 20 feet long.

Dunn said the program is designed so participants share the experience "of real world research in ways that enhance their appreciation of science and nature.’’

An avid outdoorsman who leads bird walks for Mass Audubon, he said visitors will likely see blue jays, tufted titmouses and robins flying through the tree tops or perched on branches.

Perry said wheelchair users can access the first platform to look down through the tree canopy but would not be able to navigate the walkways.

Children ages 5 to 11 must be accompanied by an adult while older children don’t require a chaperone. Small groups of up to six children and adults are admitted at 30-minute intervals. Staff suggest visitors to the Tree Canopy Walkway weight 250 pounds or less so they can fit into the safety harness.

Led by teacher Terry Miller, five students from Westminster Elementary School huddled together before stepping onto the Walkway.

Staffer Molly DeGuglielmo, a recent Clark University graduate from Concord, helped them step leg by leg into a harness which was tightened and then buckled around their waists.

Once the belt was buckled tight, she helped the youngsters attach two clamps from a rope connected to the harness to a shoulder height safety rope to ensure their safety in the rare event of a fall.

Later Miller said her students, who have learning disabilities, gained confidence from visiting the Walkway.

Page 2 of 3 - Like everyone else, I was given a protective helmet to wear that, once strapped under my chin, made me understand how former Gov. Michael Dukakis might have felt after his infamous tank ride.

At first, walking on the Walkway, particularly for a super-sized adult, felt like bouncing on a trampoline. Consisting of boards held in place by a rope framework, the bridge swayed beneath my weight.

Walking gingerly along the Walkway, firmly holding the shoulder-height rope railings, I got the first chance in many decades to look upon trees from the top down, seeing their branches spread out in an utterly new way.

At the second platform, Dunn explained visitors could see several features actual researchers might use if they were staying in a tree canopy for days or weeks at a time. These included a chair and small table for eating or writing and a storage cabinet.

As I bounced along the final walkway, canopy guide Chris Hoey reached over to hoist me up to the fourth platform.

The Holden resident said he enjoyed "working out in nature’’ because he didn’t want to be spend his days "stuffed into an office cubicle.’’

He said visitors have the choice of climbing off the canopy or riding a 90-foot zip line to the forest floor. After receiving his assurances of its complete safety and signing a release in case it wasn’t, I let Hoey strap me into a canvas chair attached to the line. He said he’d set the line’s tension so I’d descend at a moderate speed.

Looking down 40 feet to the forest floor, staffer Isak Oberg, who’d steady me as I landed, appeared Hobbit-sized.

Sensing my jitters, Hoey gave a reassuring grin, a thumbs up and nudged me off the platform.

As I slid down, leaves, branches and tree trunks rushed by. Looking up for a brief moment, I saw sunshine streaming through the canopy, illuminating the woods and thought "cool, beautiful.’’

Oberg helped me out of my harness and I felt somewhat rubber-legged from jouncing on the walkway.

Ecotarium publicist Julieanne Frost said the museum has just opened a new outdoor activity called Tree Aerial Adventures that will be suitable for adults and children. Supervised by specially trained staff, visitors get the chance to climb 30-foot tall old-growth oak trees while wearing harnesses.

She said a group pf visitors would get a two-hour privately guided tour during which a staffer would instruct them in climbing and safety procedures.

"It will give kids a real experience of seeing how arborists work with trees,’’ said Frost. "It can be a real accomplishment and a totally fun experience.’’